Structural and optical properties of dense vertically aligned ZnO nanorods grown onto silver and gold thin films by galvanic effect with iron contamination

•ZnO nanorods were grown on Au and Ag films in aqueous solution by galvanic effect.•The method is prone to metal contamination which can influence the ZnO properties.•Iron doping improves the lattice matching between ZnO and the substrate.•Energy levels of point defects are lowered and the light emission is red-shifted.•Galvanic-induced nucleation starts and proceeds continuously during the growth.